John Cage: Seven, for flute, clarinet, percussion, piano, violin, viola and violoncello

John Cage (1912-1992): Seven, for flute, clarinet, percussion, piano, violin, viola and violoncello (parts without score) (1988).
Ives Ensemble.

"Seven" consists of twenty time-brackets, nineteen of which are flexible (with respect to beginning and ending) and one of them fixed. The fixed timebrackets are different ones for each part.
The duration of all time-brackets is the same, with one exception in each part. The numbers of sounds in a time-bracket is different: one in the parts for flute, clarinet and percussion, between one to three for the violin, viola and cello parts and between three to five (per staff) in the piano part.
The sounds for the percussion part are chosen by the performer. In the percussion part, the notation uses numbers, indicating which instrument to play.